For such exit signs, the Federal Aviation Regulations (FAR) require a fairly even light intensity distribution. In particular, the FAR set limit values for the ratio between the brightest portion of the exit sign and the least bright portion of the exit sign. An exemplary limit value for this ratio is 3. In order to satisfy such limit values, prior art approaches have employed very complicated optical structures, commonly employing a large number of light sources. Such approaches have proven to be not satisfactory with respect to their reliability. Also, their production has been found to be too complicated and cumbersome.
Accordingly, it would be beneficial to provide an interior aircraft light unit that is able to satisfy such light intensity ratio requirements, is less complex to produce and has an acceptable reliability.